title: Coffee, caffeine, and risk of completed suicide: results from three prospective cohorts of American adults.
abstract: OBJECTIVE
  To evaluate the association between coffee and caffeine consumption and suicide risk in three large-scale cohorts of US men and women.
  
  
  METHODS
  We accessed data of 43,599 men enrolled in the Health Professionals Follow-up Study (HPFS, 1988-2008), 73,820 women in the Nurses' Health Study (NHS, 1992-2008), and 91,005 women in the NHS II (1993-2007). Consumption of caffeine, coffee, and decaffeinated coffee, was assessed every 4 years by validated food-frequency questionnaires. Deaths from suicide were determined by physician review of death certificates. Multivariate adjusted relative risks (RRs) were estimated with Cox proportional hazard models. Cohort specific RRs were pooled using random-effect models.
  
  
  RESULTS
  We documented 277 deaths from suicide. Compared to those consuming ≤ 1 cup/week of caffeinated coffee (< 8 oz/237 ml), the pooled multivariate RR (95% confidence interval [CI]) of suicide was 0.55 (0.38-0.78) for those consuming 2-3 cups/day and 0.47 (0.27-0.81) for those consuming ≥ 4 cups/day (P trend < 0.001). The pooled multivariate RR (95% CI) for suicide was 0.75 (0.63-0.90) for each increment of 2 cups/day of caffeinated coffee and 0.77 (0.63-0.93) for each increment of 300 mg/day of caffeine.
  
  
  CONCLUSIONS
  These results from three large cohorts support an association between caffeine consumption and lower risk of suicide.
authors.affiliation: Department of Nutrition, Harvard School of Public Health , Boston, MA , USA.
authors.forename: Michel
authors.initials: M
authors.lastname: Lucas
authors.forename: Eilis J
authors.initials: EJ
authors.lastname: O'Reilly
authors.forename: An
authors.initials: A
authors.lastname: Pan
authors.forename: Fariba
authors.initials: F
authors.lastname: Mirzaei
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Olivia I
authors.initials: OI
authors.lastname: Okereke
authors.forename: Alberto
authors.initials: A
authors.lastname: Ascherio
mesh_terms: D000328:Adult; D000368:Aged; D002110:Caffeine / Q000494:pharmacology*; D003069:Coffee / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013405:Suicide / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology; D000092864:Suicide Prevention
chemical_list: D003069:Coffee; D002110:Caffeine
keywords: Coffee; caffeine; cohorts; food-frequency questionnaires; suicide